The recent commercial print market has had a strong demand for a technique for forming images on a recording medium (substrate) other than white media, such as a transparent or translucent film or a colored paper sheet. On these recording media other than white media, white images are often formed.
PTL 1 discloses a photo-curable ink as an ink adapted to form white images. This ink contains a polymerizable compound and a solvent having a low boiling point (hereinafter referred to as low-boiling-point solvent). When this photo-curable ink is cured, the low-boiling-point solvent is volatilized. Consequently, the cured film of the photo-curable ink has many pores therein and is thus porous. The pores scatter light, so that the cured film appears to be white.